Morphological measurements of lumbar pedicles in Egyptian population using computerized tomography and cadaver direct caliber measurements

IntroductionTranspedicular spinal fixation has recently been the focus of increased attention in several institutions throughout the world, but its safety and efficacy require a precise knowledge of the lumbar pedicles and their relations with neural structures.ObjectiveIn this study, it was aimed at studying the morphometry of the lumbar pedicle in Egyptian population for more safety and better efficacy during pedicle screw fixation and assessment of the accuracy of CT pedicle measurements.Patients and methodsStudy of the lumbar pedicles was conducted using CT scanning for lumbar blocks of five cadavers together with 75 cases of lumbar disc patients to clarify the lumbar pedicle morphology in Egyptian population. Measurements of the axial length, the axial angle, the pedicle breadth, and endosteal thickness were performed on CT images obtained at the middle of the cranio-caudal axis of the pedicle of patients and cadavers. Moreover, these measurements were reviewed by direct caliper measurements in these cadavers.ResultsThis study illustrated that the axial length of pedicles is around 5 cm at all lumbar levels with negligible shortening at L4 and L5. The angels of inclination of the lumbar pedicle axis on the midline are more obtuse than the known Western measurements and becoming more obtuse from L1 to L5. The study clarified that the pedicle breadth becomes progressively thicker from L1 (6.6 mm) to L5 (18.5 mm) and the endosteal thickness follows the pedicle breadth becoming thicker at L5 (8.3 mm) than at L1 (3.8 mm). We could not detect any statistically significant difference between all the above-mentioned measurements when we compared the direct caliper measurements of the cadavers with its CT measurements and with patients CT measurements. Wide range of measurements of the lumbar pedicle for each particular level was noticed.ConclusionCT pedicle measurements are accurate indicators for the actual pedicle morphometry. The Egyptian lumbar pedicles differ in some aspects from the pedicles of other populations. The pedicle screw diameter, the screw length, and the angle of its insertion are better to be tailored according to the CT pedicle measurements of each patient.